A Patent Document 1 discloses an art that is applied to an engine arranged to switch a first driving method (for example, homogeneous combustion) on a high rotation and high load side, and a second driving method (for example, stratified charge combustion) on a low rotation and low load side on which a fuel economy efficiency is higher than that of the first driving method, and that is configured to immediately increase a depression reaction force (depression force) of an accelerator pedal when the driving region of the engine enters a boundary driving region just before the switching to the first driving region when the driving region of the engine is switched from the second driving region in which the second driving method is performed, to the first driving region in which the first driving method is performed. This increase amount of the depression force is canceled when the driving region of the engine is returned from the boundary driving region to the second driving region.
In this case, when the increase amount of the depression force is suddenly returned (decreased) in a case where the increase amount of the depression force immediately increased when the driving region enters from the second driving region to the boundary driving region is restored (returned), the accelerator pedal may be excessively depressed by that reaction. Accordingly, it is preferable to gradually return this increase amount of the depression force for preventing the excessive depression of the accelerator pedal.
However, in a case where this increase amount of the depression force is gradually returned, the increase amount of the depression force becomes small when the depression force needs to suddenly increase in the middle of the gradual return of the increase amount of the depression force. Accordingly, there is generated a problem that the driver cannot feel the sudden increase of the depression force, that is, a wall feeling which is the depression feeling of the accelerator pedal.